Recently, Organic Light-Emitting Diodes (OLEDs) have become important light-emitting elements in flat display devices, because of the advantages such as instantaenous light emission, high contrast, wide color gamut, low power consumption, easy implementation of flexible displays, etc.
In a plurality of pixel circuits of an OLED display panel, each pixel includes a driving transistor therein, wherein a threshold voltage of the driving transistor often has an effect on a current flowing through the OLEDs. Due to difficulties in the manufacturing process, it is impossible for each driving transistor to have exactly identical performance parameters, and this effect of the threshold voltage on the current causes the display panel to have the problem of uneven brightness.